Synchronous sampling of rotating elements in a fault detection system having audio analysis and method of using the same

ABSTRACT

A fault detection system for determining whether a fault exists with a rotating element of a vehicle. The system includes a transducer, a diagnosis sampler, a sensor, and a controller. The transducer may be a microphone located in the vehicle for converting sounds to an electrical signal. The electrical signal includes a noise component generated from the rotating element. The diagnosis sampler is connected to the transducer and provides a sample of the electrical signal from the transducer to the controller. The sensor obtains data relating to the rotating element. The controller has functional aspects such as a synchronous resample, a spectrum analysis, and a fault detect. The synchronous resample has the capability of synchronizing the sample of the electrical signal with the data from the sensor to form a synchronized envelope. The spectrum analysis has the capability of forming a spectra from the synchronized envelope of the electrical signal, where the spectra is associated with the noise component generated from the rotating element. The fault detect has the capability of determining (from the formed spectra) whether the fault exists with the rotating element. There is also a method of detecting a fault associated with a rotating element in a vehicle using the above-described system.

[0001] The present application claims priority from provisionalapplication, Serial No. 60/373,157, entitled “Synchronous Sampling ofRotating Elements in a Fault Detection System Having Audio Analysis andMethod of Using the Same,” filed Apr. 17, 2002, which is commonly ownedand incorporated herein by reference in its entirety. Moreover, thispatent application is related to co-pending, commonly assigned patentapplication, Ser. No. ______, entitled “Fault Detection System HavingAudio Analysis and Method of Using the Same,” filed concurrentlyherewith and incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] This invention in general relates to the detection of faults in avehicle and, more particularly, to synchronous sampling of rotatingelements in a fault detection system having audio analysis and a methodof using the same.

BACKGROUND OF THE INVENTION

[0003] A user of a vehicle may hear an unpleasant sound or feel astrange vibration while operating a vehicle. Most users of vehicles arenot trained to know or recognize the source of such a sound or vibrationand in many cases significant changes over longer periods of time are sosubtle they go undetected. Many unpleasant sounds and strange vibrationsare generated by faults of rotating elements in a vehicle such as thetires, the engine, the driveline, and the fan or blower of a theheating, ventilation, and air-conditioning (HVAC) system. Accordingly,there is also a need for aiding the user of a vehicle to identify thesource of unpleasant sounds or strange vibrations in the vehicle.

[0004] Various systems have been employed for detecting faults on avehicle. Existing systems require dedicated sensors outside the cabin ofa vehicle for each component on the vehicle. These sensors aresusceptible to fault over time due to exposure to corrosive and otherharsh environments.

[0005] In the past, systems have considered using an audio transducerlocated in close proximity to a component susceptible to a fault. Suchsystems, however, require multiple audio transducers if there is adesire to monitor multiple components. Additionally, these audiotransducers are susceptive to interference from sounds and vibrations ofother components. Furthermore, the sensors themselves may be susceptibleto corrosion and other faults if they are located in harsh environments.

[0006] Accordingly, further improvements are needed to known systems forthe monitoring of multiple components on a vehicle. It is, therefore,desirable to provide an improved procedure for detecting faults ofrotating elements in a vehicle to overcome most, if not all, of thepreceding problems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a block diagram of a fault detection system according toone embodiment of the present invention;

[0008] FIGS. 2A-2E are exemplary spectra diagrams for various rotatingelements on a vehicle;

[0009]FIG. 3 is a block diagram of another embodiment of a systemincorporating the fault detection system of the present invention.

[0010] While the invention is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and will be described in detail herein. However,it should be understood that the invention is not intended to be limitedto the particular forms disclosed. Rather, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

[0011] What is described is an improved system and procedure fordetecting faults associated with rotating elements on a vehicle. To thisend, in one embodiment there is a fault detection system for determiningwhether a fault exists with a rotating element of a vehicle. The systemincludes a transducer, a diagnosis sampler, a sensor, and a controller.The transducer may be a microphone located in the vehicle for convertingsounds to an electrical signal. The electrical signal includes a noisecomponent generated from the rotating element. The diagnosis sampler isconnected to the transducer and provides a sample of the electricalsignal from the transducer to the controller. The sensor obtains datarelating to the rotating element. The controller has functional aspectssuch as a synchronous resample, a spectrum analysis, and a fault detect.The synchronous resample has the capability of synchronizing the sampleof the electrical signal with the data from the sensor to form asynchronized envelope. The spectrum analysis has the capability offorming a spectra from the synchronized envelope of the electricalsignal, where the spectra is associated with the noise componentgenerated from the rotating element. The fault detect has the capabilityof determining (from the formed spectra) whether the fault exists withthe rotating element.

[0012] Another embodiment of the present invention is a method fordetecting a fault associated with a rotating element in a vehicle. Thesteps of the method include: sampling an electrical signal from atransducer in the vehicle where the electrical signal comprises a noisecomponent generated from the rotating element; synchronizing theelectrical signal with data from a sensor associated with the rotatingelement to form a synchronized envelope associated with the rotatingelement; forming a spectra from the synchronized envelope where thespectra is associated with the noise component generated from therotating element; and determining (from the formed spectra) whether afault exists with the rotating element.

[0013] A further embodiment of the present invention includes a methodfor detecting a fault associated with a plurality of rotating elementsin a vehicle. The steps of this method include: sampling an electricalsignal from a transducer in the vehicle where the electrical signalcomprises a plurality of noise components generated from the rotatingelements; synchronizing the electrical signal with data form a pluralityof sensors associated with the rotating elements to form a synchronizedenvelope associated with each rotating element; forming a plurality ofspectra from the synchronized envelopes where each spectra is associatedwith one of the noise components generated from the rotating elements;and determining (from each of the plurality of formed spectra) whether afault exists with one of the rotating elements.

[0014] Now, turning to the drawings, an example use of a fault detectionsystem for a vehicle will be explained. As will be explained in moredetail below, the fault detection system samples the sound in a cabin ofthe vehicle and uses the sampled sound as a diagnostic tool fordetermining whether a fault exists with rotating elements in thevehicle. Referring to FIG. 1, in one embodiment, a fault detectionsystem 20 generally has a transducer 22, a diagnosis sampler 24, and acontroller 26. The fault detection system 20 determines whether a faultor problem exists with one of a plurality of rotating elements 30 a, 30b, 30 c in the vehicle. Examples of rotating elements 30 a, 30 b, 30 cin the vehicle include elements such as the tires, the engine, thedriveline, and the fans or blower for the heating, ventilation, andair-conditioning (HVAC) system.

[0015] As discussed in more detail below, after analysis of the sampledsound, a signal representing a fault or problem may be transmitted bythe controller 26 to an electronic control unit (ECU) 32. The ECU 32 maythen notify the user of the vehicle via a user display panel 34 that afault or problem exists with a rotating element 30 a, 30 b, 30 c.Alternatively, or additionally, a digital signal representing the faultor problem may be transmitted via a wireless communication device 36 toa service center (shown in FIG. 3).

[0016] The transducer 22 may be a microphone located in the cabin of thevehicle. In one embodiment, the transducer 22 is a microphone used forhands-free voice calls through the wireless communication device 36. Thewireless communication device 36 is connected to the transducer 22 andto an audio speaker 38 within the cabin. The transducer 22 may also be amicrophone used for communication with a remote service center forinformation and roadside assistance. Utilizing an existing microphone inthe cabin provides the advantage of multi-tasking a single component inthe vehicle. Alternatively, a separate dedicated transducer 22 may beinstalled in the vehicle.

[0017] The transducer 22 converts sounds in the cabin of the vehicle toan electrical signal 40. In one embodiment, the electrical signal 40from the transducer 22 is an analog signal. The diagnosis sampler 24receives the electrical signal 40 from the transducer 22. The purpose ofthe diagnosis sampler 24 is to sample the electrical signal 40 from thetransducer 22 for input to the controller 26. The diagnosis sampler 24may be a separate integrated circuit from the controller 26.Alternatively, the diagnosis sampler 24 may reside within the controller26 and be an integral part of the input. The diagnosis sampler 24 allowsthe electrical signal 40 to be further analyzed by the controller 26.

[0018] In one embodiment, the diagnosis sampler 24 takes samples of theelectrical signal 40 and converts the electrical signal 40 to a formatacceptable to the controller 26. For example, if the controller 26 is adigital signal processor (DSP) controller, the electrical signal 40 isconverted to a digital signal 42. Accordingly, the diagnosis sampler 24may include components such as an amplifier and an Analog to Digital(A/D) converter. The sampling rate should depend on the frequency limitof the transducer 22. For example, in one embodiment, the samplingprocess would be at least double the highest frequency range of thetransducer. This means that for a transducer 22 that can pick up soundsup to 6 kHz, the minimum sampling rate for the diagnosis sampler 24 is12,000 samples per second. In most embodiments, the diagnosis sampler 24should be about 16,000 samples per second and having a 12 bit resolutionfor each sample.

[0019] The diagnosis sampler 24 may be configured a number of differentways to sample the electrical signal 40 from the transducer 22. In oneembodiment, the diagnosis sampler 24 is configured to continuouslysample the electrical signal 40 at select time intervals during theoperation of the vehicle. In another embodiment, the diagnosis sampler24 is configured to sample the electrical signal 40 in response to aninstruction from the electronic control unit 32 or controller 26. Theinstruction to sample the cabin sound could be sent when certain knownconditions exist within the vehicle (i.e. when a rotating element isrotating at a certain rate). Furthermore, the diagnosis sampler 24 maybe configured to sample the electrical signal 40 or be otherwiseactivated in response to an instruction from a service center (notshown) and/or the user of the vehicle.

[0020] The electrical signal 40 generated by the transducer 22 is acomposite of sound components in the cabin of the vehicle. In oneembodiment, the digital signal 42 generated by the diagnosis sampler 24will also be a composite of sound components in the cabin of thevehicle.

[0021] One component of the sampled sound will be noise from rotatingelements 30 a, 30 b, 30 c of the vehicle. In some cases, the noiserelated to the actual rotation of rotating elements 30 a, 30 b, 30 cwill be much lower in frequency than the limits of the transducer 22.For instance, if the transducer 22 is a microphone for hands-free voicecalls or information/road-side assistance services, these microphonescan only pick up sounds between the range of 400 Hz and 6 kHz.Accordingly, the transducer 22 may not directly pick up the noiserelated to the actual rotation of these rotating elements 30 a, 30 b, 30c if they are below 400 Hz. The noise associated with the rotation of arotating element 30 a, 30 b, 30 c, however, will propagate to thestructure of the vehicle (such as the chassis). Noise through thestructure of the vehicle rings in response to forces generated by therotating elements 30 a, 30 b, 30 c. It has been discovered that theringing allows a transducer 22 with limited frequency response to detectthe state of the rotating elements 30 a, 30 b, 30 c even when theelements themselves are rotating slowly relative to the pass band of theaudio system.

[0022] For example, as mentioned above, one of the rotating elements 30a, 30 b, 30 c on a vehicle may be the tires. A tire having a radius of18 inches will rotate at 560 RPM at 60 MPH. This will cause a repetitionrate of 9.3 Hz. Sounds at this frequency are too low for the microphoneto pick up much less an audible frequency for a human ear (20 Hz-20kHz). The tire assembly, however, is attached to the chassis of thevehicle. A 9.3 Hz frequency will generate a vibration to the chassis ofthe vehicle that will result in a higher frequency noise. The transducer22 will pick up the higher frequency noise from the chassis caused bythe rotating elements.

[0023] The vibration noise from the chassis is a composite of severalother vibration noises caused from other sources of the vehicle. Oneaspect of the present invention is directed to associating a noise witha particular rotating element 30 a, 30 b, 30 c from the composite ofvibration noises and analyzing that noise to determine a fault orproblem for the rotating element 30 a, 30 b, 30 c.

[0024] The controller 26 processes the digital signal 42 from thediagnosis sampler 24. A suitable controller 26 for the present inventionmay includes a digital signal processor (DSP) controller or a MotorolaMPC 5100. The controller 26 of the present invention preferably includesa number of functional blocks. In one embodiment, the controller has anenvelope detect 44, a synchronous resample 46, a plurality of spectrumanalyses 48 a, 48 b, 48 c, and a plurality of fault detects 50 a, 50 b,50 c. These functional blocks may be microcoded signal processing stepsthat are programmed as operating instructions in the controller 26.

[0025] The envelope detect 44 detects an envelope 52 from the digitalsignal 42 received from the diagnosis sampler 24. The envelope 52 isgenerated to capture the peak amplitude values of signal bursts andrings. This can be accomplished by rectification of the digital signal42 and low pass filtering. Both the rectification and the low passfiltering are done digitally. The rectification may be done by takingthe absolute value of the digital signal 42. The rectification processmay be a mathematical absolute model or other digital representationknown to those of ordinary skill in the art.

[0026] The rectified data is then applied to the low pass filter. Thecutoff frequency used for the low pass filter is implementationspecific. The cutoff frequency will typically depend on the size of therotating element (such as the size of the rotating tire). It has beenfound, however, that each of the rotating elements in a vehicle comewithin a range of 5-100 pulses per second. In a cost efficientimplementation, a suitable cutoff frequency for the low pass filteringmay be selected between 200-400 Hz. Alternatively, separate low passfiltering may be implemented for each of the rotating elements. In anyevent, as will be discussed further, the monitoring and analysis of theenvelope 52 of cabin sounds enables the detection of faults or problemswith a particular rotating element in the vehicle.

[0027] Within the envelope 52 is a mixture of sounds from the cabin ofthe vehicle that were picked up by the transducer 22. Some of thesesounds may relate to possible problems of the vehicle and some may notrelate to problems of the vehicle. The present invention includes asynchronous resample 46 to correlate and synchronize the noiseassociated with individual rotating elements 30 a, 30 b, 30 c in thevehicle.

[0028] It has been discovered that the vibration noise from the chassisor other vehicle structure generated from the rotating elements 30 a, 30b, 30 c is closely related to the rotation of that element. Accordingly,knowing the rotation of an element 30 a, 30 b, 30 c allows thecontroller 26 to synchronize the composite envelope 52 for furtheranalysis of a particular rotating element 30 a, 30 b, 30 c.

[0029] To this end, the synchronous resample 46 receives sensor data 54a, 54 b, 54 c relating to each of the rotating elements 30 a, 30 b, 30c. The sensor data 54 a, 54 b, 54 c is used to synchronize the compositeenvelope signal 52 for a particular rotating element 30 a, 30 b, 30 c.The sensor data 54 a, 54 b, 54 c is obtained from sensors 56 a, 56 b, 56c, respectively, located at each of the rotating elements 30 a, 30 b, 30c.

[0030] In one embodiment, the sensor data 54 a, 54 b, 54 c isrepresentative of the angular displacement of the rotating elements 30a, 30 b, 30 c. There are a number of ways to measure the angulardisplacement of an element. In one embodiment, the sensors 56 a, 56 b,56 c measure a passing tooth 58 a, 58 b, 58 c, respectively, on arotating wheel of the rotating element 30 a, 30 b, 30 c. For example, asensor may measure a passing tooth on a rotating wheel attached to anengine's crankshaft. As the engine runs, the sensor typically generatesa logic level signal that transitions when the sensor senses the toothand a subsequent space. As the toothed wheel rotates, responsive to thecombustion process in the running engine, the angular displacementsignal will typically be a rectangular waveform responsive to angularvelocity, or engine speed. The practice of using a toothed wheel on acrankshaft and other rotating elements is commonplace in the field ofvehicle control. Of course, those skilled in the art will recognize manyother, substantially equivalent, means and methods to measure angulardisplacement.

[0031] The sensor data 54 a, 54 b, 54 c is provided to the synchronousresample 46. The sensor data 54 a, 54 b, 54 c is used to synchronize thecomposite envelope 52 to generate synchronized envelopes 60 a, 60 b, 60c associated with each rotating element 30 a, 30 b, 30 c. Accordingly,the synchronized envelope 60 a relates to rotating element 30 a. Thesynchronized envelope 60 b relates to rotating element 30 b. Thesynchronized envelope 60 c relates to rotating element 30 c. Eachsynchronized envelope 60 a, 60 b, 60 c is then further analyzed by aseparate spectrum analysis functional block 48 a, 48 b, 48 c.

[0032] In one embodiment, the resample of the composite envelope 52includes giving the envelope signal a new scale (sampling period). Forexample, the composite envelope 52 may have a sampling period of 16,000samples per second. There is a need to resample this envelope at adifferent rate depending on the rate of the rotating elements 30 a, 30b, 30 c. The synchronous resample 46 forms a synchronized envelope 60 a,60 b, 60 c depending on the rotating rate of the rotating elements fromthe sensors 56 a, 56 b, 56 c.

[0033] The rotating element 30 a in one embodiment may be a tire on avehicle. Associated with the tire is an anti-brake system (ABS) sensor56 a that can generate data that can be used to determine the rotationalrate of the tire at a particular time. The ABS sensor 56 a will transmitdata 54 a to the synchronous resample 46. The synchronous resample 46receives the data 54 a from the ABS sensor 56 a. The ABS sensor data 54a is then used as the sampling clock to synchronize the compositeenvelope 52 to generate a tire synchronized envelope 60 a for the tirespectrum analysis 48 a. The tire spectrum analysis 48 a may then use thetire synchronized envelope 60 a as described in more detail below.

[0034] Moreover, the rotating element 30 b may be the engine of thevehicle (such as a V6 engine). Associated with the engine is acrankshaft position sensor 56 b that can generate data that can be usedto determine the rotational rate of the engine at a particular time. Thecrankshaft position sensor 56 b will transmit data 54 b to thesynchronous resample 46. The synchronous resample 46 receives the data54 b from the crankshaft position sensor 56 b. The crankshaft positionsensor data 54 b is then used as the sampling clock to synchronize thecomposite envelope 52 to generate an engine synchronized envelope 60 bfor the engine spectrum analysis 48 b. The engine spectrum analysis 48 bmay then use the engine synchronized envelope 60 b as described in moredetail below.

[0035] Furthermore, the rotating element 30 c may be the driveline ofthe vehicle. Associated with the driveline is a vehicle speed sensor 56c that can generate data that can be used to determine the rotationalrate of the driveline at a particular time. The vehicle speed sensor 56c will transmit data 54 c to the synchronous resample 46. Thesynchronous resample 46 receives the data 54 c from the vehicle speedsensor 56 c. The vehicle speed sensor data 54 c is then used as thesampling clock to synchronize the composite envelope 52 to generate adriveline synchronized envelope 60 c for the driveline spectrum analysis48 c. The driveline spectrum analysis 48 c may then use the drivelinesynchronized envelope 60 c as described in more detail below.

[0036] The present invention is not limited to analysis of the tires,engine and driveline but may include other types of rotating elementssuch as the fans or blowers in the HVAC.

[0037] Additionally, it is noted that the synchronous resample 46 aidsin the analysis of vehicle cabin noise when the rotational rates of therotating elements is changing over time. The frequency spectrum of thecabin sound will show many features related to the rotation of elementson the vehicle. As indicated earlier, rotating elements such as thetires, the engine, the driveline, and the HVAC blower lead to cabinnoise. Most of the rotating elements in a vehicle vary in speed duringthe operation of the vehicle. If samples are taken at regular timeintervals (regardless of vehicle operation), the time sampled spectrumwill change as the rotational speed of the element changes.Synchronizing the composite envelope 52 with data 54 a, 54 b, 54 cobtained from sensors 56 a, 56 b, 56 c at the rotation elements 30 a, 30b, 30 c solves the problem of varying rotational speeds duringoperation.

[0038] There is a separate spectrum analysis function 48 a, 48 b, 48 cperformed for each rotating element 30 a, 30 b, 30 c on the vehicle. Inone embodiment, the spectrum analysis uses DSP based techniques and, inparticular, uses the Fast Fourier Transform (FFT). FFT techniques, asapplied to digitized data, provides a powerful method of signal analysisby having the ability to recognize weak signals of defined periodicityburied in a composite signal.

[0039] In one embodiment, the present invention uses FFT techniques togenerate spectra that is “order” based as shown in FIGS. 2A-2E. The“orders” shown in the figures are defined as a sine wave cycle perrevolution. It has been discovered that noise generated from rotatingelements comes out at predictable orders. In other words, the amplitudeof the noise is particularly predominating at certain cycles perrevolution. This aids in determining whether a fault or problem existswith a particular rotating element 30 a, 30 b, 30 c.

[0040] For example, if the spectrum analysis 48 a is designed to analyzetire faults, the spectrum analysis 48 a may generate an “order” basedspectra as shown in FIG. 2A. Referring to FIG. 2A, a rotating tire haspredictable peak amplitude spikes at orders 1-2-3-4. The peak amplitudedecreases as the order increases until the harmonics are insignificantcompared to systematic noise. The solid line amplitude spikes 102 a-102d refer to amplitude spikes that are consistent with a rotating tirethat does not have a fault or problem with balance or suspensionlooseness. The dashed line amplitude spikes 102 a′-102 d 40 refer toamplitude spikes that are consistent with a rotating tire that has afault or problem with balance or suspension looseness. The amplitudespikes 102 a′-102 d 40 associated with a fault or problem are greaterthan the amplitude spikes 102 a-102 d associated with normal tirerotation.

[0041] If the spectrum analysis 48 b is designed to analyze enginefaults (such as a V6 engine), the spectrum analysis 48 b may generate an“order” based spectra as shown in FIGS. 2B and 2C. Referring to FIG. 2B,an engine has predictable peak amplitude spikes at orders 1-2-3 whendetermining whether the engine has a balance problem. The peak amplitudedecreases as the order increases until the harmonics are insignificantcompared to systematic noise. The solid line amplitude spikes 104 a-104c refer to amplitude spikes that are consistent with an engine that doesnot have a fault or problem with balance. The dashed line amplitudespikes 104 a′-104 c 40 refer to amplitude spikes that are consistentwith an engine that has a fault or problem associated with enginebalance. The amplitude spikes 104 a′-104 c 40 associated with a fault orproblem are greater than the amplitude spikes 104 a-104 c associatedwith normal engine operation.

[0042] Referring to FIG. 2C, an engine also has predictable peakamplitude spikes at orders 3-4-9 when determining whether there isexhaust noise (such as a leaky muffler). The peak amplitude decreases asthe order increases until the harmonics are insignificant compared tosystematic noise. The solid line amplitude spikes 106 a-106 c refer toamplitude spikes that are consistent with an engine that does not have afault or problem with exhaust noise. The dashed amplitude spikes 106a′-106 c 40 refer to amplitude spikes that are consistent with an enginethat has a fault or problem associated with exhaust noise. The amplitudespikes 106 a′-106 c 40 associated with a fault or problem are greaterthan the amplitude spikes 106 a-106 c associated with normal engineoperation.

[0043] If the spectrum analysis 48 c is designed to analyze drivelinefaults, the spectrum analysis 48 c may generate an “order” based spectraas shown in FIGS. 2D and 2E. Referring to FIG. 2D, a driveline haspredictable peak amplitude spikes at orders 1/n, 2/n, 3/n, where n isthe numerical ratio of the gearing for the rear axle. The peak amplitudedecreases as the order increases until the harmonics are insignificantcompared to systematic noise. The solid line amplitude spikes 108 a-108c refer to amplitude spikes that are consistent with a driveline thatdoes not have a fault or problem with the axle alignment or differentialnoise. The dashed amplitude spikes 108 a′-108 c 40 refer to amplitudespikes that are consistent with a driveline that has a fault or problemassociated with axle alignment or differential noise. The amplitudespikes 108 a′-108 c 40 associated with a fault or problem are greaterthan the amplitude spikes 108 a-108 c associated with normal drivelineoperation.

[0044] Referring to FIG. 2E, a driveline also has a predictable peakamplitude spikes at orders 1-2-3. The peak amplitude decreases as theorder increases until the harmonics are insignificant compared tosystematic noise. The solid line amplitude spikes 110 a-110 c refer toamplitude spikes that are consistent with a driveline that does not havea fault or problem with drive-shaft balance or a universal joint. Thedashed amplitude spikes 110 a′-110 c′ refer to amplitude spikes that areconsistent with a driveline that has a fault or problem associated withthe balance of the drive-shaft or the universal joint (such as theuniversal joint being loose). The amplitude spikes 110 a′-110 c′associated with a fault or problem are greater than the amplitude spikes110 a-110 c associated with normal driveline operation.

[0045] Accordingly, the use of the spectrum analysis 48 a, 48 b, 48 cprovides the benefit of identifying and analyzing repeating signals. Insum, rotating elements on the vehicle have predictable repeating orders.By analyzing the amplitude spikes associated with these repeatingorders, one can determine if a fault has occurred by comparing thecurrent spectra with spectra known to represent a rotating element thatis operating properly (without faults).

[0046] In one embodiment, the determination of whether a fault orproblem exists is accomplished through a series of fault detects 50 a,50 b, 50 c, associated with each rotating element 30 a, 30 b, 30 c. Asindicated above, when analyzing the spectra of a particular rotatingelement on a vehicle, it has been discovered that a fault or problem canbe detected if the peak amplitude is higher than its normal operation.Thus, in one embodiment, a predetermined threshold may be associatedwith each above-described condition.

[0047] The predetermined threshold can be implemented in a number ofways. For example, one embodiment includes an integration method todetermine the area of the amplitude spikes for the spectra. A value forthe predetermined threshold can be set that is slightly greater than thearea of the amplitude spikes that would exist for a rotating elementthat is operating properly (without faults). In other words, thepredetermined threshold should represent an acceptable value of the areaof the amplitude spikes before a fault or problem is detected with aparticular rotating element. If the area beneath the amplitude spikes(under analysis) is greater than the predetermined threshold, a faultexists with the rotating element. If the area beneath the amplitudespikes (under analysis) is less than the predetermined threshold, nofault exists with the rotating element.

[0048] In another embodiment, the predetermined threshold represents anacceptable maximum height for the amplitude spikes within the spectra.Here, the predetermined threshold is a maximum height (or value)slightly greater than a height of an amplitude spike that would existfor a rotating element that is operating properly (without faults). Whenthe amplitude spikes (under analysis) are greater than the predeterminedthreshold, a fault exists with the rotating element. In eitherembodiment, a different predetermined threshold would need to bedetermined for each type of rotating element and for each type ofproblem that may possibly exist for that rotating element. Thepredetermined thresholds may be installed by the manufacturer and basedon the type and design of the vehicle. The predetermined thresholds mayalso be determined from historical data on a fleet of vehicles of thesame make and model of vehicle.

[0049] In sum, when the amplitude spikes are at or below a predeterminedthreshold, the vehicle is determined to have no faults or problems.However, when the amplitude spikes are above the predeterminedthreshold, the vehicle is determined to have a fault or problem.

[0050] It is noted that the predetermined thresholds described hereinmay vary based on the speed of the rotating element. Accordingly, in oneimplementation of the present invention, each fault detect 50 a, 50 b,50 c contains a look-up table that can be indexed by the currentrotational speed of the rotating element 30 a, 30 b, 30 c. For thisimplementation, the fault detects 50 a, 50 b, 50 c need to have accessto the data received by the controller 26 from sensors 56 a, 56 b, 56 c.

[0051] In another implementation, the fault detects 50 a, 50 b, 50 cinclude historical averages of acceptable amplitude spikes for aparticular rotating element. For example, if the diagnosis sampler 24 issampling the vehicle cabin at regular intervals during operation, ahistorical threshold average can be developed for each rotating element.In this embodiment, the controller 26 stores in memory the amplitudespikes for different rotational speeds of the rotating elements 30 a, 30b, 30 c to develop the historical threshold average. After an acceptablehistorical threshold average has been compiled, the fault detects 50 a,50 b, 50 c would then compare the existing amplitude spikes at aspecific time to the historical threshold average at the existingrotational speed. If there was a sharp contrast between the existingamplitude spikes and the historical threshold average, then a fault orproblem would be detected by the controller 26.

[0052] If a fault or problem is determined by the controller 26, a faultsignal 62 may be provided to the user of the vehicle. In one embodiment,the fault signal 62 is provided to the electronic control unit (ECU) 32of the vehicle. In this embodiment, the ECU 32 is connected to a userdisplay panel that notifies the user of the vehicle that a fault orproblem exists with a particular rotating element 30 a, 30 b, 30 c.

[0053] In another embodiment of the present invention, as shown in FIG.3, the fault detection system 20 is used in connection with a Telematicssystem. The Telematics system includes a fault detection system 20(within a vehicle 70) and a service center 80.

[0054] The fault detection system 20 and the service center 80 maycommunicate with each other via wireless communications. The wirelesscommunications are illustrated in FIG. 3 by communication arrows A andB. Communication arrow A may represent a communication by the user ofthe vehicle 70 asking the service center 80 for help in analyzing aproblem with the vehicle 70. Communication arrow A may also represent acommunication by the fault detection system 20. This communication couldbe a fault signal 62 generated by the controller 26. Alternatively, thecontroller 26 may directly send the synchronized envelopes 60 a, 60 b,60 c or raw spectra data directly to the service center 80. The servicecenter 80 would then perform the fault detect functions. The advantageof this approach is that it allows the flexibility of changing thepredetermined thresholds based on historical data from fleet studies onvehicles with the same make and model.

[0055] Communication arrow B may represent a communication by theservice center 80 instructing or informing the user of the vehicle 70 ofthe type of fault or problem that may appear to exist with the vehicle70. In a further embodiment, the diagnosis sampler 24 may be configuredto take a sample of the audio within the cabin of the vehicle on demandby the service center 80 through communication arrow B.

[0056] As shown in FIG. 3, in one embodiment, the communications A and Bmay be a cellular wireless communication that is sent through the publicswitched telephone network (PSTN) 82, a cellular network 84, and a basestation antenna 86. Those of ordinary skill in the art, having thebenefit of this disclosure, will appreciate that many possible wirelesscommunication methods may be used for communications between the vehicle70 and the service center 80. In one embodiment, the communications arevia a cellular wireless communication such as AMPS, CDMA, GSM, or TDMA.The transmission between the vehicle 70 and the service center 80 mayalso be made by other wireless communications such as satellitecommunications.

[0057] Having the fault detection system 20 wirelessly connected to aservice center 80 has several benefits as will be apparent from thefollowing description. The user of a vehicle 70 having the faultdetection system 20 may hear a noise or believes that the vehicle 70 isnot responding properly. The user of the vehicle 70 may push a button inthe vehicle 70 to establish a wireless communication with the servicecenter 80. The service center 80 receives the fault signals 62 from thevehicle 70 via the wireless communication device 36 (as shown in FIG.1). The service center 80 may then look at the fault signals 62. Ifthere is a fault or problem, the service center 80 may inform the userof the vehicle 70 of the apparent problem. For example, it may appearfrom the fault signals 62 that there is a severe misalignment problemwith the axle. The service center 80 may then instruct the user of thevehicle that the vehicle should be taken (or even towed) to a carfacility immediately. Alternatively, it may appear from the faultsignals 62 that there is a problem with the HVAC fan or blower. Theservice center 80 may then inform the user of the vehicle 70 that theproblem does not appear to be serious but instruct the user to turn offthe air conditioning.

[0058] The above description of the present invention is intended to beexemplary only and is not intended to limit the scope of any patentissuing from this application. The present invention is intended to belimited only by the scope and spirit of the following claims.

What is claimed is:
 1. A fault detection system for determining whethera fault exists with a rotating element in a vehicle, the fault detectionsystem comprising: a transducer located in the vehicle for convertingsounds to an electrical signal, the electrical signal comprising a noisecomponent generated from the rotating element; a diagnosis sampler,connected to the transducer, for providing a sample of the electricalsignal from the transducer; a sensor for obtaining data relating to therotating element; a controller, connected to the diagnosis sampler andthe sensor, having a synchronous resample, a spectrum analysis, and afault detect, the synchronous resample having the capability ofsynchronizing the sample of the electrical signal with the data from thesensor to form a synchronized envelope, the spectrum analysis having thecapability of forming a spectra from the synchronized envelope, thespectra being associated with the noise component generated from therotating element, and the fault detect having the capability ofdetermining from the formed spectra whether the fault exists with therotating element.
 2. The fault detection system of claim 1, wherein thetransducer is a microphone within a cabin of the vehicle.
 3. The faultdetection system of claim 1, wherein the electrical signal converted bythe transducer is an analog signal and the sample provided by thediagnosis sampler is a digital signal.
 4. The fault detection system ofclaim 1, wherein the spectrum analysis of the controller includes a fastFourier transform.
 5. The fault detection system of claim 1, wherein thefault detect of the controller includes a comparison between anamplitude of the formed spectra and a predetermined threshold.
 6. Thefault detection system of claim 5, wherein the predetermined thresholdrepresents an area of an amplitude of a spectra where the rotatingelement does not have a fault.
 7. The fault detection system of claim 5,wherein the predetermined threshold represents a maximum allowableheight of an amplitude of a spectra where the rotating element does nothave a fault.
 8. The fault detection system of claim 1, wherein thecontroller further has an envelope detect having the capability ofdetecting an envelope of the electrical signal from the diagnosissampler prior to the formation of the synchronized envelope.
 9. A methodfor detecting a fault associated with a rotating element in a vehicle,the method comprising the steps of: sampling an electrical signal from atransducer in the vehicle, the electrical signal comprising a noisecomponent generated from the rotating element; synchronizing theelectrical signal with data from a sensor associated with the rotatingelement to form a synchronized envelope associated with the rotatingelement; forming a spectra from the synchronized envelope, the spectrabeing associated with the noise component generated from the rotatingelement; determining from the formed spectra whether the fault existswith the rotating element.
 10. The method of claim 9, wherein thetransducer is a microphone within a cabin of the vehicle.
 11. The methodof claim 9, wherein the step of forming the spectra from the envelopeincludes a fast Fourier transform.
 12. The method of claim 9, whereinthe step of determining whether the fault exists includes a comparisonbetween an amplitude of the formed spectra and a predeterminedthreshold.
 13. The method of claim 12, wherein the predeterminedthreshold represents an area of an amplitude of a spectra where therotating element does not have a fault.
 14. The method of claim 12,wherein the predetermined threshold represents a maximum allowableheight of an amplitude of a spectra where the rotating element does nothave a fault.
 15. The method of claim 9 comprising the further step ofsending a fault signal to an electronic control unit of the vehicle whenit is determined that a fault exists with the rotating element.
 16. Themethod of claim 9 comprising the further step of detecting an envelopeof the electrical signal, the envelope comprising the noise componentgenerated from the rotating element, the step of detecting the envelopeof the electrical signal performed prior to the step of synchronizingthe electrical signal.
 17. The method of claim 9 comprising the furtherstep of transmitting a fault signal to a service center representingwhether the fault exists with the rotating element.
 18. A method fordetecting whether a plurality of faults exist with a plurality ofrotating elements in a vehicle, the method comprising the steps of:sampling an electrical signal from a transducer in the vehicle, theelectrical signal comprising a plurality of noise components generatedfrom the rotating elements; synchronizing the electrical signal withdata from a plurality of sensors associated with the rotating elementsto form a synchronized envelope associated with each rotating element;forming a plurality of spectra from the synchronized envelopes, eachspectra being associated with one of the noise components generated fromthe rotating elements; determining from each of the plurality of formedspectra whether one of the faults exist with one of the rotatingelements.
 19. The method of claim 18, wherein the transducer is amicrophone within a cabin of the vehicle.
 20. The method of claim 18,wherein the step of forming the plurality of spectra from thesynchronized envelopes includes a fast Fourier transform.
 21. The methodof claim 18, wherein the step of determining whether one of the faultsexist includes a comparison between an amplitude of the formed spectraand a predetermined threshold.
 22. The method of claim 18 comprising thefurther step of sending a fault signal to an electronic control unit ofthe vehicle when it is determined that one of the faults exist with oneof the rotating elements.
 23. The method of claim 18 comprising thefurther step of detecting an envelope of the electrical signal, theenvelope comprising the noise components generated from the rotatingelements, the step of detecting the envelope of the electrical signalperformed prior to the step of synchronizing the electrical signal. 24.The method of claim 18 comprising the further step of transmitting afault signal to a service center when it is determined that one of thefaults exist with one of the rotating elements.